Biology is a dialogue between reduction and integration. This Center will combine the powers of the two approaches by using a reductionist idea, the functional module, to investigate the integration, organization, and evolution of cells. The proposal has three goals: 1) To ask how well the idea of the functional module helps us to understand the organization, behavior, and evolution of cells and organisms. We define a functional module as a collection of molecules that exists to perform a specific function that contributes to an organism's survival and reproduction (and we explain the concept more fully below). We will analyze and evolve modules and the connections among them, identify them computationally, study how they allow long-term evolvability to coexist with short-term robustness, ask how they affect interactions among mutations in evolution, and examine the role of modules at multiple levels in the interplay between social behavior and gene expression. 2) To build and train a truly collaborative group of scientists who share a single guiding vision, the interplay between theory and experiment, rather than a common training, or a devotion to a particular, narrow problem. The team includes theoretical physicists, mathematicians, computer scientists, and biologists, works on organisms from bacteria to fish, and spans five institutions in two countries. 3) To conduct an experiment in the organization of biological research. Most of the work will be done at Harvard University's Bauer Center Genomics Resarch, whose nucleus is a group of nine young research fellows, who from the start of their independent careers will be committed to the goal of interdisciplinary research. The Center of Excellence's mission is to encourage collaboration among the fellows, and between them and the students, post-docs, and faculty in surrounding departments, thus nucleating a larger community that is dedicated to using a variety of approaches to looking for principles that explain biology.